Disk drives are widely used in computers and data processing systems for storing information. These disk drives commonly use magnetic storage disks to store data in digital form. In order to obtain higher storage capacities, disk drives have evolved from utilizing a single rotating, storage disk, to utilizing a plurality of spaced apart, rotating, storage disks.
Each storage disk typically includes a data storage surface on each side of the storage disk. These storage surfaces are divided into a plurality of narrow, annular, concentric regions of different radii, commonly referred to as "tracks." Typically, an actuator assembly is used for precisely positioning a data transducer proximate the appropriate track on the storage disk to transfer information to and from the storage disk.
The need for increased storage capacity and compact construction of the disk drive has led to the use of disks having increased track density, i.e., more tracks per inch. With these systems, the accurate and stable positioning of the data transducer proximate the appropriate track is critical to the accurate transfer and/or retrieval of information from the rotating storage disks.
As is well known in the art, the rotating storage disks are excited by internal and external vibration of the disk drive. This vibration causes axial motion in the rotating disks which is transferred to the data transducers. This can lead to errors or delays in the transfer of data caused by the inaccurate positioning of the data transducer relative to the tracks on the rotating disks. This is commonly referred to as "track mis-registration."
Additionally, the need to rapidly access information has led to disk drives having storage disks which rotated at higher speeds. Presently, disk drives having disks which rotate at approximately 7,200 RPM and higher are available. Unfortunately, a significant portion of the internal vibration can be attributed to windage effect on the rotating disks. Thus, higher rotational speeds of the storage disks often result in increased levels of vibration of the rotating disks and increased occurrences of track mis-registration.
One attempt to solve this problem includes changing the design of each storage disk to reduce the amplitude of the vibration. For example, prototype storage disks have been made which utilize a pair of disk shaped aluminum substrates which are separated by an annular shaped viscous material. However, with this type of design, the distance between the disks fluctuates significantly with temperature changes.
Another attempt to solve this problem includes positioning an viscoelastic ring in series with a rigid spacer between adjacent disks. However, this attempt has also proven to be unsuccessful because compression in the viscoelastic ring allows for movement of the storage disks. This leads to track mis-registration.
In light of the above, it is an object of the present invention to provide a disk assembly for a disk drive having reduced levels of vibration. Another object of the present invention is to provide a more stable and accurate disk drive. Still another object of the present invention is to provide a disk drive which utilizes a plurality of high speed, high density storage disks.